Calcium acetate fluid lubricants



United States Patent 3,328,299 CALCIUM ACETATE FLUID LUBRICANTS Arnold J. Morway, Clark, and Rudolph Kassinger, Westfield, N.J., assignors to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Filed Dec. 1, 1965, Ser. No. 510,94 4 Claims. (Cl. 25240.7)

This invention relates to calcium acetate fluid lubricants, having improved stability and clarity, and which are particularly useful for cylinder lubrication of marine diesel engines. These lubricants comprise lubricating oil, calcium acetate as an antiwear agent, certain surfactants for maintaining the calcium acetate suitably dispersed in the oil to give a fluid product, and a high molecular weight monocarboxylic acid as a gel prevention agent which permits easy filtering to reduce haze and sediment.

In lubricating marine diesel engine cylinders, the lubricant should have good antiwear propertiesand'be of fluid consistency for pumping through the centralized forcedfeed lubrication system and to evenly spread and wet the piston, and cylinder. The lubricant should be storage stable, and heat stable so that it does not gel or unduly thicken when moving through hot feed lines or when it contacts the surface of the hot cylinder which it is to lubricate.

Lubricants for such marine diesel lubrication, which substantially met the preceding requirements, have been made by dispersing calcium acetate as an antiwear agent in mineral lubricating oil, with calcium salt of C to C fatty acid as suspending agent for the oil-insoluble calcium acetate. Usually, these lubricants are made by coneutralizing with lime, the acetic and C to C fatty acid in situ in the oil. Recently, it was found that having phosphosulfurized (usually P 8 treated) polyisobutylene present during the coneutralization, particularly when using C to C fatty acid (preferably containing at least some unsaturation), was very effective in further improving the stability, i.e. preventing separation and gelling at high temperatures. Also, this lubricant can be made filter-.

able to a haze-free product. However, this requires relatively large quantities of the phosphosulfurized polyisobutylene and the odor then becomes objectionable. When using smaller quantities, the odor is acceptable, but in large scale production, a gel is present which causes these lubricants to rapidly plug the filter. It has now'been found that adding a high molecular weightpolyolefin monocarboxylic acid acts to prevent gel and permits easy filtering of the lubricant without undue plugging of the filter.

The calcium acetate lubricants of the invention will therefore comprise lubricating oil, and the coneutralized mixture of acetic acid, C to C fatty acid and phosphosulfurized polyisobutylene, and an unneutralized high molecular weight polyolefin monocarboxylic acid. This polyolefin monocarboxylic acid is added after the other acids have been coneutralized and dehydrated, so as to avoid reacting the polyolefin monocarboxylic acid. Also, the coneutralized mixture is usually made so that it is on the acid side whereby there is no base available for reaction with said polyolefin monocarboxylic acid.

The oil component of the lubricant is preferably mineral lubricating oil, although synthetic lubricating oils such as Ucon oils, ester oil, polycarbonate oils, polysilicone oil, etc. can be used. In some cases when the synthetic oil might tend to react with the lime or acetic acid, the preformed salts can be dispersed directly in the synthetic oil.

While saturated fatty acids can be used, the unsaturated C to C fatty acids are preferred since generally they will give a more fluid product. Such preferred fatty 3,328,299 Patented June 27, 1967 ice acids will include tallow fatty acids, oleic, palmitoleic, gadoleic, erucic, arachidonic, myristoleic acid, etc. These fatty acids are usually derived from either animal or vegetable sources. In some cases, commercial fatty acid derived from naturally occurring materials will contain both saturated and unsaturated acid. For example, some commercial fatty acids will contain about 40 or even 60 wt. percent of saturated fatty acids, with the remainder being principally mono-unsaturated fatty acid along with minor amounts of polyunsaturated fatty acid. Trace amounts of lower fatty acid may also be present. These commercial mixed saturated and unsaturated fatty acid materials will usually have Wijs iodine numbers of about 35 to 110, preferably 40 to 80, and saponification numbers of 250 to 150, preferably 225 to 175, mg. KOH/ gm.

Phosphosulfurized polyisobutylene is well known and can be prepared by reacting phosphorus pentasulfide with polyisobutylene of 600 to 4,000, preferably 700 to 1400, Staudinger molecular weight for about 0.5 to 15 hours at 150 to 600 F.

The starting material for the high molecular weight polyolefin acid is a polymer of a C to C monoolefin, e.g. polyethylene, polypropylene, or polyisobutylene, having an average molecular weight (Staudinger) of about 600 to 3000, preferably 800 to 1900. Polyisobutylene is preferred since it has a lessened tendency to gel the product, as compared to some of the other polyolefins such as polyethylene and polypropylene. The polymer is halogenated by blowing either bromine or chlorine, preferably the latter, through the polymer to provide about one to two atoms of halogen per molecule of polymer. The halogenation step may be conducted in the temperature range of from about 50 to about 300 F. To aid in the halogenation step, the polymer may be dissolved in a suitable solvent, such as carbon tetrachloride, in order to lower the viscosity of the polymer. However, the use of such a solvent is not necessary.

The time required for halogenation may be varied to some extent by the rate at which the halogen is introduced. Ordinarily from about 2 to about 5 hours is a satisfactory halogenation period. In a representative plant scale operation involving the chlorination of polyisobutylene of 830 molecular weight, a -pound batch will be chlorinated with 10 pounds of chlorine introduced into the reactor over a period of 3 /2 hours with a chlorination temperature of about 250 F.

The halogenated polymer thus obtained is condensed with an alpha,beta-unsaturated, monocarboxylic acid of from 3 to 8 carbon atoms. Ordinarily, because of their greater availability, acids of this class having 3 or 4 carbon atoms will be used. Such acids include acrylic acid, alphamethylacrylic acid (i.e., 2-methyl propenoic acid) and crotonic or isocrotonic acid (beta-methylacrylic acid). Other alpha,beta-unsaturated acids that may be employed include tiglic acid (alpha, methylacrotonic acid), angelic acid (alpha-methylisocrotonic acid), sorbic acid, and cinnamic acid. Esters of such acids, e.g. ethyl methacrylate, may be employed if desired in place of the free acid.

In condensing the halogenated polyolefin with the unsaturated acid, at least one mole of acid is used per mole of halogenated polyolefin. Normally, the acid will be employed in excess and may amount to as much as 1.5 to 2 moles per mole of halogenated polyolefin. The condensation temperature may be in the range of from about 300 to 500 F. and will more preferably be Within the range of from about 375 to 475 F. The condensation may require from about 3 to about 24 hours, but will ordinarily take place in from 6 to 18 hours.

After the reaction has ben completed, excess acid may be purged from the mixture, for example, by blowing with a stream of nitrogen at a temperature of 400 to The high molecular weight carboxylic olefin acids of the invention may also be prepared by a so-called onestep process involving the halogenation of the o'lefin polymer in the presence of the alpha,beta-unsaturated acid. Using proportions of reactants within the ranges discussed above, the starting acid and the olefin polymer are mixed together in the reactor, the temperature being kept below about 150 F. until the start of halogen introduction so as to avoid homopolymerization of the alpha,beta unsaturated acid. Once halogenation has begun, the temperature may be raised to as high as 250 F. After halogen introduction the temperature may be raised to 300 to 500 F. to effect the condensation reaction.

While the method of first chlorinating the polyolefin and then condensing with unsaturated acid is the preferred way, because of simplicity, of forming the high molecular weight polyolefin acids used in the invention, other techniques can be used since the method of making the acid is not material. For example, the polyolefin can be converted to a monocarboxylic acid by the x0 process wherein the polyolefin is reacted with carbon monoxide and hydrogen using a cobalt carbonyl catalyst to form an aldehyde/alcohol mixture which is then oxidized to the acid. Oxidation of the polyolefin with nitric acid will also form the desired high molecular weight monocarboxylic acid. These and other techniques are described in detail in British Patent specification 983,040 published Feb. 10, 1965. Still other techniques are known in the art.

Based upon 100 parts by weight of the finished fluid lubricant, the finished lubricant of the invention will generally comprise a major amount of mineral oil and a coneutralized mixture of 1.0 to 7.0, preferably 2 to 6, parts of acetic acid; 0.2 to 5.0, preferably 0.3 to 1.0, parts of C to C fatty acid; and 0.5 to 5.0, preferably 0.5 to 2.0, parts of P S treated polyisobutylene. The lubricant will contain .2 to 3.0, preferably .2 to 1.0, parts of the unreactedolefin acid.

The lubricant is preferably first made as a concentrate by dispersing lime, the C to C acid and a major proportion of the phosphosulfurized polyisobutylene in about /2 to /6 of the oil, then adding the acetic acid very slowly while stirring, e.'g. over a 5 to 10 hour period in large batches, so as to keep the temperature of the mass below about 200 F. Preferably, the mixture is recycled from the grease kettle through a homogenizer or grease mill, and then back to the kettle, while the acetic acid is being added. This prevents agglomeration of the calcium acetate and results in a finer particle size for [the calcium acetate. The mixture is then dehydrated at about 225 to 350 F. to remove the water of reaction. The polyolefin acid is next added and the mixture is preferably filtered while hot, e.g. 250 to 300 F., so as to keep the viscosity low, and while using diatomaceous earth filter aid. After filtration any additional additives can be added. The concentrate is then diluted with the remainder of the oil to form the final lubricant.

It will be understood that various minor modifications of the preceding procedure can be utilized without departing from the inventive scope of the invention. For example, preformed calcium acetate, and/ or preformed calcium soap of the aforesaid higher fatty acid component may be added to the oil and heated together with the phosphosulfurized polyolefin, or the calcium salt of the phophosulfurized polyolefin. Or the phosphosulfurized polyolefin or its salt can be added to the composition after the in situ neutralization of the acetic and higher fatty acid. However, this later procedure is not preferred, since it appears to result in a more viscous product than when the metal salts of the acetic and higher fatty acid are formed in oil in the presence of the phosphosulfurized polyolefin.

Various additives can be added to the finished lubricant in amounts of 0.1 to 10.0 wt. percent, based on the weight of the finished lubricant. Among additives that can be added are: corrosion inhibitors such as sodium nitrite, lanolin, wool grease stearine; antioxidants such as phenyl-a-naphthylamine; dyes; asphaltic oils to aid in reducing haze caused by water; etc.

The invention will be further understood by reference to the following examples wherein all parts are by weight and which include a preferred embodiment of the invention.

Polyisobutenyl propionic acid was prepared as follows: A solution was prepared consisting of 2000 parts of polyisobutylene of 950 molecular weight dissolved in 1000 parts of carbon tetrachloride. Chlorine gas was bubbled through the stirred solution at room temperature, i.e. about 75 F. for a period of four hours. Following the chlorination step, the carbon tetrachloride solvent was removed from the mixture by purging with nitrogen while maintaining the mixture at 285 F. The resulting chlorinated polyisobutylene had a chlorine content of 4.33 wt. percent.

A mixture of 600 parts of the chlorinated polyisobutylene thus prepared and 55 parts of acrylic acid was heated at 450 F. for a period of 18 hours. Hydrogen chloride was evolved from the mixture during this heating. The mixture was then purged with nitrogen for one-half hour while the mixture was maintained at 450 F after which the mixture was cooled to 250 F. and filtered through Dicalite (diatomaceous earth) filter aid. The product, identified as olyisobutenyl propionic acid, contained 0.3 weight percent of chlorine and had a saponification number of 52.1 mg. KOH/gm.

Run I-A.--Preparati0n of mixed salt concentrate A mixed salt concentrate was prepared as follows:

55.04 parts of mineral lubricating oil of 60 SUS viscosity at 210 F., 14.14 parts of hydrated lime, 3.51 parts of tallow fatty acid, and 4.18 parts of phosphosulfurized polyisobutylene dissolved in 20 wt. percent mineral lubrieating oil, were mixed together in a steam jacketed grease kettle. The kettle contents were mixed and homogenized by recycling through a Charlotte colloidal mill and then back to the kettle. Then 22.35 parts of glacial acetic acid was slowly added over a period of about 6 hours while mixing and homogenizing by said recycling, and while keeping the temperature below 150 F. The grease mixture was then externally heated, while continuing mixing by said recycling through said Charlotte mill, to 300 F. to 330 F. This temperature range was held about 60 minutes in order to remove all free water and leave the calcium acetate in its half hydrate form, i.e.

(CH COO) (Ia-0.5 H O The product, which was slightly on the acid side, was then cooled and 0.27 part of phenyl-alpha-naphthylamine was added. The product was then further cooled to 100 F. Mixing by said homogenizing was continued during the entire process, including cooling. An excellent smooth product resulted, which was fluid at room temperature.

However, attempts to filter this product while at 250 F. through a plate and frame filter press using 1.0 wt. percent Celite (diatomaceous earth) filter aid were unsuccessful because a gel formation quickly covered the diatomaceous earth coating on the filter causing plugging of the filter after only a few drums of product were filtered.

The phosphosulfurized polyisobutylene used above was prepared by reacting polyisobutylene of about 800 Standinger molecular weight with 15 wt. percent P S based on the weight of the polyisobutylene at about 425 F. for about 8 hours under a nitrogen atmosphere, and then diluted to the wt. percent concentrate in lubricating oil.

The tallow fatty acid used 'above had a Wijs iodine number of about 50 and a saponification number of 205.

Run IB.-Preparation of finished lubricant 'Als'o, the table shows that the polyisobutenyl propionic acid resulted in a lower viscosity material (Examples I-B and LC) as compared to the same composition without this acid (Run LB), which is a desirable result. Further- 1855 parts of the unfiltered concentrate of Run I-{ 5 more, it was found that the concentrate material Without was mixed with 81.45 parts of additional mineral lu rlthe acid, for example the composition of Run I-A, will eating oil having a viscosity of about 80 SUS at 210 F. increase in viscosity'during storage of about three months The resulting mixture was homogenized and gave a hazy until it gels and becomes a solid grease composition. This fluid composition. interferes with shipping concentrate in drums to foreign Example IA ports for subsequent dilution with oil. However, adding Run I-A was repeated exactly except that 2.5 parts of polylspblltflnyl .proplomc i for m 21/2 polyisobutenyl Propionic acid was added after the grease cent, inhibits this gel formation and maintains the concenhad been cooled to 280 F. following the formation of ggi g; claimed the calcium a etate half h drate.

c y 1. A substantially haze-free fluid lubricant suitable for Example l-B use for cylinder lubrication of marine diesel engines comprising a major amount of lubricaitng oil; a lime concug gg zg g ig ggf i 52 522; g iizi gif I A tralized mixtrue of 1 to 7 wt. percent of acetic acid, 0.2 to 5 wt. percent of C to C fatty acid and 0.5 to 5 wt. per- Example I-C 0 cent of P 8 treated polyisobutylene of 600 to 4000 mo- A portion of the product of Example I-A was filtered lecular weight. to S percent of a polyolefin While about B through a Plate and frame fine-r using IIlOllOCfil'bOXYllC acid wherein said polyolefin group has a 1% diatomaceous earth premixed with the product, After moficular i of 600 to 3000 and ls a polymer of a C2 filtering then 18.55 parts of the filtered product was mixed 25 to 5 monoo. e with 81.45 parts of additional mineral lubricating oil. 1 A 11113116311t accordlflg t0 Clalm Whefln Said Oil s The compositions and properties of the preceding mamineral lubricating oil, said fatty acid has a Wijs iodine terials are summarized in the following table: number of to 110 and a Saponification number of 250 TABLE Run I-A Run I-B Ex. I-A Ex. I-B Ex. I-o

Composition (Wt. Percent):

Glacial Acetic Acid 22. 35 4.15 22. 35 4.15 4.15

Tallow Fatty Acid 3. 51 0.65 3. 51 0. 65 0. 65

80% sol. P285 treated poly obutylene 4.18 0. 78 4. 18 0. 78 0. 78

Hydrated Lime 14. 63 2. 72 14. e3 2. 72 2. 72

Phenyl a-naphthylarnine 0. 27 0. 05 0. 27 0. 05 0. 05

Mineral lubricating oil, 60 SUS at 210 55. 04 10. 20 52. 56 9.74 9. 74

Polyisobutenyl propionic acid 2. 0. i6 0. 46

Mineral lubricating oil, 80 SUS at 210 F..- 81. 45 81. 45 81. 45

Properties:

Filterability at 250 F Appearance SUS Vise, at 100 F. SUS Vise, at 210 F SUS Visc., at 100 F.+1.0% H2O Ash (02.80;) percent Total Base No. Centrifuge (Vol. perce sedlmeut) As Is +01% H O +02% 1110---.

1 Clear to slight haze.

It was not practical to filter the concentrate of Run IA during large scale manufacturing due to rapid plugging of the filter. As a result, dilution of this concentrate to form the final fluid product of Run I-B resulted in a hazy appearing material. The concentrate of Example 1-A, representing the invention, contained the high molecular weight polyolefin monocarboxylic acid which permitted this concentrate to be readily filtered to give a clear concentrate. This clear filtered concentrate, when diluted to form the product of Example I-C resulted in a clear to a very slightly hazy material (clear at 100 F. and above, very slight haze below 100 P.) which was very stable in the Centrifuge test, even when contaminated with water. On the other hand, Example I-B, made from an unfiltered portion of the same concentrate of Example I-A, showed considerably more haze and contained a relatively large volume of sediment. Thus, the preceding table clearly demonstrates that the addition of the high molecular weight carboxylic acid prevents gel formation and thereby permits easy filterability to thereby reduce haze and sediment. This, in turn, increases the marketability of the product since the presence of haze is frequently considered by the user to be a sign of an inferior product which can cause operational difficulties.

to 150, and said polyolefin acid is polyisobutenyl propionic acid.

3. A method of preparing the lubricant of claim 2, which comprises dispersing said P 8 treated polyisobutylene, said lime and said fatty acid in about /2 to /6 of the total amount of said lubricating oil, slowly adding said acetic acid While keeping the temperature of the reaction mass below about 200 F., dehydrating said mixture at a temperature of about 225 to 375 F. to remove the water of reaction, adding said polyisobutenyl propionic acid as a gel prevention agent, and then filtering said mixture, then diluting said mixture by the addition of the remainder of said oil to thereby form a substantially haze-free fluid lubricant.

4. A substantially haze-free fluid lubricant suitable for cylinder lubrication of marine diesel engines comprising a major amount of mineral lubricating oil, a lime eoneutralized mixture of 2 to 6 Weight percent acetic acid, 0.3 to 1.0 weight percent of C to C fatty acid having a Wijs iodine number of 40 to and a saponification number of about 225 to mg. KOH/g., .5 to 2.0 wt. percent of P 8 treated polyisobutylene having an average molecular weight of about 800 to 1900, and .2 to 1.0 wt. percent of polyisobutenyl propionic acid formed by condensing a 7 halpgenated polyisobutylene of 800 to 1900 molecular 2,846,392 9/1958 Morway 'et a1 25240.7 wexght wlth acryhc acld. 2,944,022 7/1960 Ulzheimer et a1 252-56 References Cited 3,125,521 3/1964 Detweiler et a1. 25240.7 UNITED STATES PATENTS 5 DANIEL E. WYMAN, Primary Examiner. 2,334,996 11/ 1943 Davis 25256 C F, DEES, W, H. CANNON, Assistant Examiners.

2,824,131 2/1958 Di Nardo et a1 25256 

1. A SUBSTANTIALLY HAZE-FREE FLUID LUBRICANT SUITABLE FOR USE FOR CYLINDER LUBRICATION OF MARINE DIESEL ENGINES COMPRISING A MAJOR AMOUNT OF LUBRICATING OIL; A LIME CONEUTRALIZED MIXTURE OF 1 TO 7 WT. PERCENT OF ACETIC ACID, 0.2 TO 5 WT. PERCENT OF C12 TO C30 FATTY ACID AND 0.5 TO 5 WT. PERCENT OF P2S5 TREATED POLYISOBUTYLENE OF 600 TO 4000 MOLECULAR WEIGHT; AND 0.2 TO 3.0 WT. PERCENT OF POLYOLEFIN MONOCARBOXYLIC ACID WHEREIN SAID POLYOLEFIN GROUP HAS A MOLECULAR WEIGHT OF 600 TO 3000 AND IS A POLYMER OF A C2 TO C5 MONOOLEFIN. 